Atelisite-(Y) is an uncommon silicate mineral characterized by its distinctive yttrium content and prismatic crystal habit. It is primarily found in complex alkaline pegmatites, often associated with other rare-earth-bearing minerals.

Hardness

6-7

Mohs

Luster

Vitreous

Streak

Colorless

Transparency

Transparent

mineralrareGadolinite Group family

Atelisite-(Y)

Hardness: 6-7
Luster: Vitreous
Streak: Colorless
Transparency: Transparent

No image

Is this atelisite-(y)?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch atelisite-(y) with a known reference. Atelisite-(Y) sits at Mohs 6-7, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: colorless.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: colorless, pale brown.
5
Look at form & habit
Crystal system: tetragonal. Typical habit: prismatic crystals.

Often confused with

Atelisite-(Y) vs. its common look-alikes, and how to tell them apart in the field.

mineral

Gadolinite-(Y)

Mohs 6.5-7

How to tell apart: Streak differs, so Atelisite-(Y) leaves colorless, Gadolinite-(Y) leaves greenish gray.

How to tell apart: Streak differs, so Atelisite-(Y) leaves colorless, Thortveitite leaves gray.

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All properties

Chemical formula: Y₄Si₃O₈(OH)₈
Mohs hardness: 6-7
Density: 4.26 g/cm³
Colors: Colorless Pale brown
Streak: Colorless
Luster: Vitreous
Transparency: Transparent
Crystal system: Tetragonal
Crystal habit: Prismatic crystals
Rarity: Rare
Uses: Collector
Host rock: A late, hydrothermal mineral in dissolution cavities in fluorite in niobium-yttrium-fluorine (NYF) type, quartz-microcline pegmatite

Where rockhounds find atelisite-(y)

Classic worldwide localities

Stetind quarry, Tysfjord, Nordland, Norway

Field-hunting tip

Where it forms: A late, hydrothermal mineral in dissolution cavities in fluorite in niobium-yttrium-fluorine (NYF) type, quartz-microcline pegmatite. If you start seeing xenotime-, calcioancylite-, la-dominant calcioancylite in float, you are in the right ground. Typical habit: prismatic crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify atelisite-(y)?+

Mohs hardness is 6-7. Luster: vitreous. The streak is colorless. Common colors include colorless, pale brown.

Where is atelisite-(y) found?+

Notable localities include Stetind quarry, Tysfjord, Nordland, Norway.

Is atelisite-(y) safe to handle?+

Contains minor rare earth elements and thorium which can cause radioactivity; handle with care and wash hands after handling.

What rocks look like atelisite-(y)?+

Atelisite-(Y) is most often confused with Gadolinite-(Y), Thortveitite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with atelisite-(y)?+

Atelisite-(Y) commonly co-occurs with Xenotime-, Calcioancylite-, La-dominant calcioancylite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does atelisite-(y) form in?+

Where it forms: A late, hydrothermal mineral in dissolution cavities in fluorite in niobium-yttrium-fluorine (NYF) type, quartz-microcline pegmatite. Working float back to the host body is the standard way to chase a fresh occurrence.

What is atelisite-(y) used for?+

Atelisite-(Y) is used in collector.

Find atelisite-(y) on the map

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